Databases - What is the difference between indexes for HEAP MyISAM and MERGE MySQL tables?
Some of the most important things concerning indexes for the different table types are listed below: MyISAM BLOB and TEXT indexes can exist. Null values are permissible in indexes MERGE A MERGE table contains no indexes of its own. HEAP Use a hash index stored in memory, which is very fast. Can only use indexes with the = and <=> operators. Cannot use an index on a column that allows NULL values. Indexes are not used with an ORDER BY clause